Separation of vanadium and chromium in solution after vanadium precipitation by co-extraction with N263 and selective stripping with NaOH solution

The conventional process of extracting vanadium from vanadium slag produces a large amount of V-Cr-bearing residue (VCBR) and wastewater containing sulfate and ammonium salt. Through the research of the co-extraction and selective stripping of vanadium and chromium, this work proposes a novel process for extracting vanadium and chromium from vanadium slag to avoid the issues mentioned above. Methyl tri octyl ammonium carbonate (N263) can co-extract vanadium and chromium from solution after vanadium precipitation. Vanadium can be selectively stripped by NaOH solution from the loaded organic solution containing V and Cr. Under the most suitable conditions, including NaOH concentration of 3 mol/L, stripping temperature of 25 degrees C, O/A ratio of 3:1, the stripping of vanadium and chromium reached more than 99% and less than 8%, respectively, after five-stage counter current stripping. Chromium in the loaded organic solution can be stripped in the form of PbCrO4.PbO precipitate using the stripping system of PbCO3 + NaOH solution. Under the most suitable conditions, including PbCO3 addition with a Pb/Cr molar ratio of 5, NaOH concentration of 0.5 mol/L, O/A ratio of 1:1, stripping temperature of 25 degrees C, stripping time of 50 min, the stripping of chromium reached 99.1%.

Automated summary

A novel process has been proposed to extract vanadium and chromium from vanadium slag to avoid issues related to V-Cr-bearing residue and wastewater. The co-extraction and selective stripping techniques can efficiently separate vanadium and chromium. By optimizing the operational conditions, effective extraction and stripping of vanadium and chromium can be achieved.